The Inhibitor of DNA binding (ID) proteins belong to the class V HLH family of transcription factors. Four ID proteins (ID 1-4)are known in humans. Unlike the basic HLH (bHLH) transcription factors, ID proteins lack the basic DNA binding region. They can heterodimerize with class I bHLH transcription factors to form inactive complexes. They thus act as dominant negative inhibitors of the class I bHLH transcription factors. They are also capable of regulating the activity of class II HLH transcription factors. Since, class I and II HLH proteins regulate the expression of cell type-specific genes and differentiated phenotype, ID proteins are thought to regulate the cross-talk between the pathways involved in cell growth and differentiation. Aberrant expression of ID proteins are found in many primary tumors and are found to regulate many steps in cancer progression including neo-angiogenesis, invasion and migration, proliferation and growth, cell-cell interaction and differentiation. These include head and neck squamous cell carcinoma, esophageal squamous cell carcinoma, melanoma, hepatocellular carcinonoma, pancreatic cancer, ovarian cancer, cervical cancer, breast cancer and prostate cancer. Among the transcription factors that ID proteins associate with are the Ets family members (ELKs) and paired box family (PAXs). They can also bind to the retinoblastoma and retinoblastoma-like proteins (RBLs), which are thought to be tumor suppressors. IDs can also be phosphorylated by CDK2. Please access this pathway at [http://www.netpath.org/netslim/id_pathway.html NetSlim] database. If you use this pathway, please cite following paper: Kandasamy, K., Mohan, S. S., Raju, R., Keerthikumar, S., Kumar, G. S. S., Venugopal, A. K., Telikicherla, D., Navarro, J. D., Mathivanan, S., Pecquet, C., Gollapudi, S. K., Tattikota, S. G., Mohan, S., Padhukasahasram, H., Subbannayya, Y., Goel, R., Jacob, H. K. C., Zhong, J., Sekhar, R., Nanjappa, V., Balakrishnan, L., Subbaiah, R., Ramachandra, Y. L., Rahiman, B. A., Prasad, T. S. K., Lin, J., Houtman, J. C. D., Desiderio, S., Renauld, J., Constantinescu, S. N., Ohara, O., Hirano, T., Kubo, M., Singh, S., Khatri, P., Draghici, S., Bader, G. D., Sander, C., Leonard, W. J. and Pandey, A. (2010). NetPath: A public resource of curated signal transduction pathways. <i>Genome Biology</i>. 11:R3. ae2 Addition of serum stimulates ID2 phosphorylation in quiescent TIG-3 cells. ID2 interacts with RBL2 in TIG-3 fibroblasts. ID2 interacts with PAX2 in NIH 3T3 and Cos-7 cells. ID2 interacts with RBL1 in TIG-3 fibroblasts. ID2 interacts with SAP2 in Cos-7 cells. ID3 interacts with MYOD1 in HeLa cells. ID2 interacts with RB1 in TIG-3 fibroblasts. ID1 interacts with SAP1 in Cos-7 cells. ID2 interacts with PAX5 in NIH 3T3 and Cos-7 cells. ID2 interacts with PAX8 in NIH 3T3 and Cos-7 cells. signaling pathway PW:0000003 Pathway Ontology 20067622 PubMed NetPath: a public resource of curated signal transduction pathways. Genome Biol 2010 Kandasamy K Mohan SS Raju R Keerthikumar S Kumar GS Venugopal AK Telikicherla D Navarro JD Mathivanan S Pecquet C Gollapudi SK Tattikota SG Mohan S Padhukasahasram H Subbannayya Y Goel R Jacob HK Zhong J Sekhar R Nanjappa V Balakrishnan L Subbaiah R Ramachandra YL Rahiman BA Prasad TS Lin JX Houtman JC Desiderio S Renauld JC Constantinescu SN Ohara O Hirano T Kubo M Singh S Khatri P Draghici S Bader GD Sander C Leonard WJ Pandey A Inhibitor of DNA binding signaling pathway PW:0001372 Pathway Ontology